JP3232164B2 - Ultrasonic sensors for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle ultrasonic sensor for detecting an obstacle.

[0002]

2. Description of the Related Art As an ultrasonic sensor, an ultrasonic vibrator is driven to transmit an ultrasonic pulse intermittently, and a reflected wave of the ultrasonic wave is received by the ultrasonic vibrator. There is a so-called reflection type that detects the presence of a hologram. In this ultrasonic sensor, a specific period (hereinafter, referred to as a detection gate period) after transmission of an ultrasonic wave is set, and when a reflected wave is received during the detection gate period, it is determined that an object is present. It is. In other words, by setting the detection gate period, malfunction due to reverberation vibration of the ultrasonic transducer is prevented,
In addition, unnecessary detection of a distant object is prevented.

A vehicle equipped with this type of ultrasonic sensor is used to alert a driver when an obstacle is present to recognize the presence of the obstacle and to assist driving. Have been.

[0004]

By the way, in this type of conventional vehicle ultrasonic sensor, since the sensor portion is mounted outside the vehicle, raindrops adhere to the sensor portion. When raindrops adhere to the sensor unit in this manner, the reverberation of the ultrasonic vibrator may be continued for a long time, and the reverberation may be continued until a detection gate period for setting an area for detecting an obstacle. Therefore, in the related art, a malfunction is prevented from occurring at the time of rainfall by delaying a time when the detection gate is opened (a rising time when a gate signal for setting the detection gate period becomes a high level).

However, if the time when the detection gate is opened is delayed in this way, a reflected wave from an obstacle located in a short distance will not be detected as an obstacle. That is, there is a problem that a non-detection area in front of the sensor unit becomes large. The present invention has been made in view of the above points, and an object of the present invention is to provide a vehicle ultrasonic sensor capable of minimizing a non-detection area as much as possible.

[0006]

According to the first aspect of the present invention, there is provided a horn-structured protective rubber.
Raindrop detector that detects the attachment of raindrops to a vibrated ultrasonic transducer
When a raindrop is detected by the step and the raindrop detection means,
Raindrop removal means that shakes off by adding motion
Means for detecting raindrops on a flexible printed circuit board
Provided on the protective rubber as a flexible printed wiring board
A vibrating film to vibrate is kept as raindrop removal means.
Between the protective rubber and the flexible printed wiring board.
It is characterized by that .

According to a second aspect of the present invention , in addition to the configuration of the first aspect,
Te, disabled to further ensure safety giving an alarm to the person or vehicle as harmful matter (who ride the car), when an obstacle is detected, alarm that emits an alarm to the outside of the vehicle It has.

[0008]

The invention according to claim 1 is configured as described above.
To make flexible printed wiring boards with vibration film
Vibration causes raindrops to adhere to the ultrasonic vibrator.
To remove the state of vibration and increase the reverberation vibration of the ultrasonic vibrator.
Remove the elephant itself. This makes it possible to determine whether it is raining or not.
Regardless, it is possible to prevent the non-detection area from becoming wide. Ma
Also, a vibration for vibrating the flexible printed wiring board
Protective rubber and flexiv using moving film as raindrop removal means
Since it is interposed between printed wiring boards, the entire protective rubber
Ultrasonic vibration compared to when vibrating to remove raindrops
Adhered to the gap between the child and the flexible printed wiring board
Vibration is easily transmitted directly to raindrops, and it is also used for protection rubber.
It can reduce the reverberation.

[0009] In the present invention of claim 2, when the obstacles are detected, by providing the alarm which emits an alarm to the outside of the vehicle, person or car as an obstacle (person to ride the car)
For safety.

[0010]

EXAMPLES An embodiment of the present invention will be described based on Embodiment 1 FIGS. 1 to 12. The ultrasonic sensor of the present embodiment also
The ultrasonic vibrator is driven to transmit ultrasonic pulses intermittently, and the ultrasonic wave reflected by the object is received by the ultrasonic vibrator, and during the detection gate period set according to the detection area. This is a so-called reflection type that detects the presence of an obstacle when a received wave output is obtained.

First, a circuit configuration of an example of an ultrasonic sensor will be described with reference to FIG. In this ultrasonic sensor,
The transmission period for transmitting ultrasonic pulses from the ultrasonic transducer 1 and the gate width of the detection gate period are determined by an integrating circuit 2, a monostable multivibrator (hereinafter abbreviated as monostable multi) 3, and a switching circuit 4. To decide. here,
The integration circuit 2 starts the integration operation at the same time when the power is turned on, and triggers the monostable multi 3 when the integration level reaches a certain potential. Then, when the monostable multi 3 is triggered, the switching circuit 4 discharges the charge of the capacitor constituting the integration circuit 2 and makes the integration circuit 2 start the integration operation again. That is, the cycle at which the monostable multi 3 is triggered by the output of the integrating circuit 2 is the transmission cycle of the ultrasonic wave. Further, a fixed period from when the monostable multi 3 is triggered to return to the stable state is the gate width of the detection gate period.

The pulse width of the ultrasonic pulse transmitted from the ultrasonic transducer 1 is determined by the monostable multi 5. The monostable multi 5 is triggered by an output when the monostable multi 3 is triggered, and a certain period of time from when the monostable multi 5 is triggered to when the output returns to a stable state is defined by the ultrasonic vibrator 1. Is the pulse width of the ultrasonic pulse transmitted from.

It is the oscillation circuit 6 and the driver 7 that drive the ultrasonic vibrator 1 according to the output from the monostable multi 5 to transmit the ultrasonic waves. Oscillation is performed during a period in which the output is given until the output is triggered and returns to a stable state.
Signal for driving the Then, the driver 7 converts the high-frequency signal into a signal of a level necessary for driving the ultrasonic vibrator 1 and transmits ultrasonic waves from the ultrasonic vibrator 1.

The signal received by the ultrasonic transducer 1 is amplified and detected by an amplifier 8 and a detector 9. That is, the amplification circuit 8
Then, a weak reception output of the ultrasonic vibrator 1 is amplified, a high frequency component included in the amplification output is removed by a detection circuit 9, and so-called envelope detection for extracting only the envelope of the amplification output is performed. Based on the amplified detection output, the level detection circuit 10, the integration circuit 11, and the gate circuit 12 determine whether or not the received signal is a reflected wave from an object present in the detection area.

The level detection circuit 10 compares the detection output with a certain level and determines whether the detection output is higher than a certain level. The level detection circuit 10 converts the detection output into a so-called rectangular wave which is high when the detection output is higher than a certain level, and is low when the detection output is lower, so that a fine noise component having a low level is obtained. Are removed by the level detection circuit 10.

The output whose level has been determined is supplied to the integrating circuit 1.
It is determined whether or not the temporal width at 1 (this width may be considered as a pulse width since it has been converted into a rectangular wave by the level detection circuit 10) is equal to or greater than a predetermined width. In other words, if this time width is narrow, it is removed as noise or the like,
When the time width is equal to or more than a certain width, the output of the integration circuit 11 reaches a predetermined level.

The integration operation of the integration circuit 11 is performed only during the output period of the gate circuit 12. The gate circuit 12 outputs the monostable multi 3 with a delay for a predetermined time, and sets a detection gate period corresponding to the detection area. The integration circuit 11 is enabled to perform the integration operation only during the detection gate period set by the gate circuit 12. As a result, the received signal outside the detection gate period is all removed by the integration circuit 11 because it is not a reflected wave by an object present in the detection area.

A switching circuit 13 is provided at the output of the integration circuit 11, and a buzzer Bz is driven each time the output of the integration circuit 11 is obtained, thereby issuing a warning to the driver. The configuration described above is a configuration also including a conventional ultrasonic sensor of this type. The operation related to the above circuit section will be briefly described. The ultrasonic transducer 1 is driven by the output of the driver 7 shown in FIG. Then, when an object, that is, an obstacle is present in the detection area, a reflected wave from the obstacle is received by the ultrasonic vibrator 1 as shown by (b) in FIG. Note that the output A in FIG. 3 is due to the direct vibration of the ultrasonic transducer 1. The output obtained by amplifying the reception output of the ultrasonic transducer 1 by the amplification circuit 8 is detected by the detection circuit 9 as shown in FIG.
The detection output is applied to a reference level (FIG.
Compare L ₁₎ and shown in (c), if the reference level L ₁ or level detection output shown in FIG. 2 (d) is obtained.
The pulse width of the output is determined by the integration circuit 11, and it is determined whether or not the output is present in the detection gate period set by the gate circuit 12 shown in FIG. 2 (e). Provides a detection output. When this detection output is obtained, the buzzer Bz by the switching circuit 15 is driven. Here, the switching circuit 15
Has a function of maintaining the state once a detection output is obtained from the integration circuit 11 for a certain period of time.

As shown in FIG. 3 (a), a sensor section S having the ultrasonic transducer 1 as a main component is mounted on a bumper B, a buzzer Bz is arranged in the vehicle, and the sensor section S and the buzzer Bz are connected to each other. 1, that is, the circuit block C is housed inside the body A. The sensor unit S is shown in FIG.
As shown in (1), the housing 20 is composed of the base 20a and the cover 20b, and the ultrasonic vibrator 1 is fitted in the protective rubber 21 and mounted in the mounting recess of the base 20a. The connection of the wiring 30a for connecting the sensor unit S and the buzzer Bz to the circuit block C is performed using a harness connector. The attachment of the sensor section S to the bumper B is performed by an attachment piece 20a integrally projecting from the housing 20, as shown in FIG.

The portion of the protective rubber 21 located on the front side of the ultrasonic vibrator 1 has a horn structure whose diameter increases toward the front, and functions to give the ultrasonic vibrator 1 a certain directivity. ing. With such a structure of the protective rubber 21, a structure is provided in which raindrops easily adhere to the gap between the ultrasonic vibrator 1 and the protective rubber 21 (portion indicated by a in FIG. 2). Focusing on this point, since the raindrop is attached to the gap of the ultrasonic vibrator 1 and the protective rubber 21 (indicated by a in FIG. 2), it is to be detected whether the rainfall. For this purpose, as shown in FIG. 5, a flexible printed circuit board 22 is attached to the inside of the horn portion of the protective rubber 21, and a portion of the flexible printed circuit board 22 corresponding to the gap a is
A pair of electrodes 23a formed of a linear copper foil pattern are formed along the circumferential direction. Now, assuming that raindrops adhere to the gap a due to rainfall, the attached raindrops (indicated by C in the figure) short-circuit the electrodes 23a, and it is possible to detect rainfall from this short-circuit state.

The output of the raindrop detector 23 comprising the pair of electrodes 23a is input to the gate circuit 12, as shown in FIG. The drive signal given to the ultrasonic vibrator 1 when no raindrop is detected by the raindrop detector 23 is shown in FIG.
The output of the amplifier circuit 8 is shown in FIG.
And the gate signal output from the gate circuit 12 is shown in FIG. Here, the reverberation vibration of the ultrasonic vibrator 1 means the vibration after the drive signal is removed in (b) of FIG.

When a raindrop is detected, reverberation vibration continues for a long time as shown in FIG. Therefore,
As shown in FIG. 2B, upon receiving the output of the raindrop detector 23, the gate circuit 12 delays the rising point of the gate signal. Even if a reverberation signal is present, a malfunction does not occur due to reverberation vibration if the level is equal to or lower than the detection level L1 of the level detection circuit 10 shown in FIG. In view of this, the gate signal rises when the level of the reverberation vibration becomes equal to or lower than the detection level of the level detection circuit 10. With this configuration, the detection gate period is adjusted only during rainfall, so that there is no problem that the non-detection area near the sensor unit S becomes wide except during rainfall. the above
In the case of the example shown in FIG.
In the present embodiment, the processing was handled by the
This is to remove attached raindrops. This implementation
In the example, as shown in FIG.
Vibration film 24 is interposed between plate 22 and protective rubber 21
Then, as shown in FIG. 12, the raindrop detection described in the first embodiment is performed.
When a raindrop is detected by the section 23, the vibrating film 24 is shaken.
The excitation signal generation circuit 25 to be activated is provided in the circuit block C.
It is. That is, raindrops due to rain fall on the gap a.
When it arrives, it is detected by the raindrop detector 23 and an excitation signal is generated.
The vibrating film 24 is vibrated by the raw circuit 25 so that raindrops
Shake from a. By doing so, the circuit block C
The side has a fixed detection game regardless of whether it is raining or not.
Obstacles can be detected during the monitoring period. And the rain
It also affects the directivity of the sensor unit S and bounces off the road surface
Problem that ultrasonic waves are received and cause malfunctions
is there. Therefore, conventionally, ultrasonic waves that bounce off the road surface are detected.
Sensor so that it is not received within the
The mounting position of the part S was raised. In this case,
Than the maximum detection distance corresponding to the falling point of the
It is necessary to mount the sensor unit S at a high position,
Large undetected area below the vehicle (this undetected area
A blind spot). But the book
As in the embodiment, the raindrop attached to the ultrasonic vibrator 1 is removed.
By doing so, the ultrasonic waves bouncing off the road surface will be received,
It does not cause a malfunction and there is a large malfunction under the vehicle.
There is no problem that a detection area is generated. Note that the vibration
The vibration frequency of the film 24 is transmitted by the ultrasonic vibrator 1.
Because it is sufficiently lower than the frequency of the ultrasonic wave,
The sound does not reach the ultrasonic transducer 1. But the vibration
It is preferable to take measures to avoid adding to the ultrasonic transducer 1 as much as possible.
New

By the way, in the conventional ultrasonic sensor for a vehicle which detects an obstacle, a warning is given to a driver. Warning function has been removed. For example, when an ultrasonic sensor is used to detect an obstacle present behind a vehicle, a driver knows the presence of the obstacle behind. However, from the viewpoint of the vehicle, a person or a vehicle (a occupant) that is an obstacle is dangerous because the vehicle equipped with the ultrasonic sensor does not know that the vehicle comes back.

This embodiment is designed to improve this point. In this embodiment, the upper part of the sensor unit S is provided as shown in FIG.
As shown in (b), there is provided an alarm unit 26 which is a display for giving a warning to a person who is an obstacle or a person who gets in the vehicle. As shown in FIG. 7, the alarm unit 26 may perform lighting control using the output of the switching circuit 13.
In this case, a timer 14 is provided between the integrating circuit 11 and the switching circuit 13. This timer 14
Is a so-called off-delay operation for holding the output state of the integration circuit 13 for a certain period of time after the obstacle is no longer detected.

In the above case, the alarm section 26 is integrated with the sensor section S, but may be separate as shown in FIGS. 8 and 9. FIG. 10 shows a circuit diagram in that case. In the above-described case, the case in which the warning in the vehicle is issued by the buzzer Bz has been described. Similarly, the alarm unit 26 may be a buzzer, a sound generator, or a combination thereof with a display. Further, it is needless to say that the alarm unit 26 may be provided separately in any part of the vehicle as long as a person as an obstacle can easily be recognized.

[0026]

[0027]

[0028]

[0029]

According to the first aspect of the present invention, as described above, the horn
Attaching raindrops to ultrasonic transducers held by structural protective rubber
Raindrop detecting means for detecting arrival and detection of raindrops by the raindrop detecting means.
Removes raindrops that are shaken off by applying vibration to raindrops when issued
And a flexible printer provided with a raindrop detector.
A wiring board is provided on the protective rubber as a means for detecting raindrops.
Vibration film for vibrating shivle printed wiring boards
The raindrop removal means as protective rubber and flexible print
Since it is interposed between wiring boards, it is flexible with a vibrating film.
By vibrating the printed circuit board,
Remove the condition that the raindrops adhere to the moving element, and remove the ultrasonic vibrator.
It is possible to eliminate the phenomenon that the sound vibration becomes longer,
As a result, regardless of whether it is raining or not,
It can be prevented from becoming wide. Ma
Also, a vibration for vibrating the flexible printed wiring board
Protective rubber and flexiv using moving film as raindrop removal means
Since it is interposed between printed wiring boards, the entire protective rubber
Ultrasonic vibration compared to when vibrating to remove raindrops
Adhered to the gap between the child and the flexible printed wiring board
Vibration is easily transmitted directly to the raindrops, removing the raindrops
And a protective rubber
Protection compared to removing the raindrops by vibrating the whole
The reverberation that occurs in rubber can be reduced,
Even when removing raindrops, reverberation vibration is generated in the ultrasonic vibrator.
Reduces transmission and prevents undetected areas from widening
Is what you can do.

[0030]

According to the second aspect of the present invention, when an obstacle is detected, an alarm which issues an alarm to the outside of the vehicle is provided. An alarm can be given and safety can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an example of an ultrasonic sensor .

FIG. 2 is an explanatory diagram of a basic operation of the embodiment.

FIGS. 3 (a) and 3 (b) are an explanatory view showing a state where the above is mounted on a vehicle, and an explanatory view showing a mounting state of a sensor unit.

FIG. 4 is a sectional view of a main part of a sensor unit.

FIG. 5 is a partially broken perspective view showing the structure of a further important part of the sensor unit.

FIG. 6 is an explanatory diagram of an operation of a main part of the above.

FIG. 7 is a circuit diagram when a sensor unit equipped with an alarm unit is provided.

FIG. 8 is an explanatory diagram showing a method of arranging a warning unit separately from a sensor unit.

FIG. 9 is an explanatory diagram showing an arrangement portion of an alarm unit in an enlarged manner.

FIG. 10 is a circuit diagram when the alarm unit is separate from the sensor unit.

FIG. 11 is a sectional view of a main part of a sensor unit according to one embodiment of the present invention.

FIG. 12 is a circuit diagram of the same.

[Explanation of symbols]

 1 ultrasonic transducer 12 gate circuit21 Protective rubber 22 Flexible printed wiring boards  23 Raindrop detector 24 Vibration film 26 Alarm

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-160388 (JP, A) JP-A-63-27784 (JP, A) JP-A-63-228091 (JP, A) 64558 (JP, A) JP-A-4-363998 (JP, A) JP-A-5-45456 (JP, A) JP-A-5-1557849 (JP, A) JP-A-62-280575 (JP, A) Japanese Utility Model Showa 58-164960 (JP, U) Japanese Utility Model Showa 63-183575 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S ^7/ 52-7/64 G01S 15/00 -15/96

Claims (2)

(57) [Claims] An ultrasonic transducer is driven to transmit an ultrasonic pulse intermittently, a reflected wave of the ultrasonic wave by an object is received by the ultrasonic transducer, and a gate circuit is provided in accordance with a detection area. In the ultrasonic sensor for a vehicle that detects the presence of an obstacle when the received wave output is obtained during the detection gate period set in the above, the attachment of raindrops to the ultrasonic vibrator held by the protective rubber of the horn structure and rain detection means for detecting, when the raindrop is detected by the rain detection device, swing the addition of vibration to the raindrop overlooked
Fleximeter equipped with a raindrop detector
The printed circuit board is mounted on the protective rubber as a means for detecting raindrops.
Vibration to vibrate the flexible printed wiring board.
Protective rubber and flexiv using moving film as raindrop removal means
An ultrasonic sensor for a vehicle, which is interposed between printed wiring boards . 2. When an obstacle is detected, the vehicle moves outside the vehicle.
Claims characterized by comprising an alarm for issuing an alarm
Item 2. The vehicle ultrasonic sensor according to item 1.